Abstract: A mobile telephone terminal is tested by a test set transmitting to the terminal on a downlink a predetermined data pattern which it recognises and which prompts it to transmit an access request on an uplink. The access request is analysed by the test set to assess the performance of the terminal without the test set otherwise responding to the access request from the terminal. Multiple different data patterns may be used such that each prompt the terminal to transmit an access request to a different power level and/or specify a different maximum number of times the terminal should send an access request if it receives a response to none of them. The predetermined data pattern may be transmitted multiple times at different power levels and the response of the terminal analysed to determine a threshold at which it fails to transmit an access request.